1. Field
The present teachings relate to RF (radio frequency) circuits. More particularly, the present teachings relate to methods and apparatuses for reducing receiver interconnections in an RF front-end stage via usage of an RF switch with integrated tuning.
2. Description of Related Art
Radio frequency (RF) devices, such as cell phone transmitters, are becoming increasingly complex due to additional frequency bands, more complex modulation schemes, higher modulation bandwidths, and the introduction of efficiency improvement schemes such as envelope tracking. Standard transceiver integrated circuits (ICs) used in communication systems, such as cell phones, contain numerous input/output pins some of which are dedicated to receive/process signals/data received through, for example, an antenna. Such dedicated inputs are typically configured as differential inputs for optimal noise immunity and referred to as low noise amplifier (LNA) inputs. Furthermore, to achieve optimum performance in receiving the data (e.g. reception channel), the LNA input needs to be matched to the source impedance under consideration of the properties of the printed circuit board on which the transceiver IC is assembled, This matching is typically done via matching circuits (e.g. RLC networks) placed between the input source (e.g. signal) and the LNA input of the IC and designed to have a relatively narrow passband corresponding to a frequency band of interest (e.g., center frequency f0 of the band). Taking into consideration for various communication frequency bands (e.g. using different center frequencies) different matching circuits feeding different LNA inputs may be needed. Such configuration can increase the number of components required in an RF device which in turn can increase the complexity of routing the various components as well as cost associated with the device. Furthermore, with the usage of diversity antennas with the aim to reduce fading effects on a detected signal by building into the RF device redundant receive paths tuned to receive signals from the diversity antennas, more design and manufacturing challenges can be expected.